The present invention relates to an apparatus that includes a blade for leveling paving material. More specifically, the apparatus includes a signal generator for measuring the elevation of a road so that the blade can be adjusted to create a more planar road.
Blades have not been used to level viscous asphalt mixtures such as substantially solventless and/or cold asphalt mixtures. Instead, blades are used for grading roads before mix is laid rather than being used to lay the mix.
Screeds have been used to even out paving material as it is being applied to a surface. The disadvantage with traditional screeds is that they do not work well for spreading solventless and/or cold mix, which can be quite viscous. While laying such mixtures, screeds grab and pull the mix as it is being applied.
Conventional adjustment mechanisms for screeds, whether manual or electronic, change the tilt or angle of attack of the screed but do not lift the screed. In order to continue to lay a planar road when the stiffness of the paving mixture increases, the forward speed of the screed must be slowed or the angle of attack of the screed must be adjusted. Even in doing either or both, the ride of the finished pavement is compromised.
Lift cylinders adjust the downward pressure of the screed and raise it for mobilization. After the screed is lifted up by the cylinders, it floats in a downward direction being pulled by the weight of the screed. It floats on the pavement mixture because of the upward force induced by the mixture but is never in suspension.
Some screeds are manually adjusted in response to elevational changes in the road. However, this delayed adjustment merely exaggerates the elevational changes creating more severe raised sections and indentations in the road.
In order to overcome these disadvantages, a device for evening out sections of mix placed on high and low elevations of a road is needed. More specifically, this device should be significantly more responsive to changes in the elevation of the road than conventional devices.